can't sit in seiza

Hey, guys. New to the site and forums.

So I can't sit in the seiza position. I don't mean "Oh it hurts when I sit in it for a minute :(((((((" I mean I literally can't get into the position. If I had to estimate, when I try I get about an inch to two inches from my heels and then I come to a dead stop. If I pushed it any harder (and I've tried right up to the point where I thought I might pop my kneecaps off) I think my knees would explode. I also can't squat, for reference.

I'm 18, about 6'2, 215-220lbs, and very out of shape. Now, it could be that plus me being really inflexible, and if that's the case, let me know. I've never had some major injury or was in gymnastics or something. But I did have Osgood Schlatter's when I was younger from growing too quickly. My knees bugged me throughout middle school and most of high school, but were never diagnosed with anything more severe.

I guess what I'm wondering about is if anyone has heard of someone experiencing this before and if they fixed it - and how. If I have to do some excersize for my knees every day, I will, so just let me know.

Also, isn't it weird there's NO topic in the forums with "seiza" in the title? Huh.

There's 2 people in my class that can't do it, so they basically sit 'up' on there knee's. Nobody points / laughs / calls them on it because quite frankly their bodies literally won't allow them to do it any other way, and anyone who is a dick tends to get the **** kicked out of them during sparring.

I had problems with seiza and it bugged the hell out of me. I'm 193cm high (6'4"), not flexible, I have flat feet and I can barely bend my feet fingers in the direction of my face, so I basically can't sit seiza on my toes until today. But the sitting itself on the knees is much better than when I started to train, it hurts much less and I can sit longer this way. I still can't sit all the way down and it hurts a lot if someone pushes me down when I'm in seiza, but I still train like everyone else.
In Daito-Ryu practice, every time we do 10 techniques when both practitioners are in seiza, and also 5 more when one is in seiza and the other standing, so its about an hour on the knees every time, I sometimes get cramps and my knee hurts, not to mention in many techniques my disability for not being able to sit on my toes puts me in a big disadvantage' but I manage! And it doesn't affect my progress.

I've jacked up my ankles so much playing soccer that seiza hurts after a few seconds. Don't worry about it. Plenty of people can't do it. The Japanese sit like that everyday their whole lives, so for them it's just natural.

I would be concerned with your inability to squat. That's something you need to fix.